Center for Urban Energy Research, Korea Institute of Science and Technology, Hwarang-ro 14-gil 5, Seongbuk-gu, Seoul 136-791, Republic of Korea.
Soft Matter. 2018 Nov 14;14(44):8912-8923. doi: 10.1039/c8sm01691g.
The study focuses on the effect of thermal deformation degree of polyacrylonitrile (PAN) particles on the electrorheological (ER) properties of their suspensions. The heat-treated PAN particles are manufactured as ER materials using a thermocatalytic processes. The molecular structures of ER materials are analyzed to confirm a stabilization or a carbonization degree. We categorized the prepared ER particles into three basic types according to their deformation degree: Thermal dried PAN, stabilized PAN, and pre-carbonized PAN. The raw, stabilized, and pre-carbonized PAN particle-dispersed suspensions showed positive ER properties. The ER properties are enhanced as the heat-treatment temperature increases due to improved dielectric property. However, the thermal dried PAN particle ER suspensions showed negative ER behavior though the particles have higher conductivity and dielectric constants than those of the host fluid, which is contrary to the conduction model. XRD results indicate that the ER materials could show contradictory ER behavior even if they have the same molecular structures due to their crystallinity. This discovery is expected to boost the development of both positive ER and negative ER suspensions based on carbonaceous ER materials.
本研究专注于聚丙烯腈（PAN）颗粒的热变形程度对其悬浮液电流变（ER）性能的影响。采用热催化工艺将热处理后的 PAN 颗粒制成 ER 材料。分析 ER 材料的分子结构以确认其稳定化或碳化程度。我们根据变形程度将制备的 ER 颗粒分为三种基本类型：热干燥 PAN、稳定化 PAN 和预碳化 PAN。原始、稳定化和预碳化 PAN 颗粒分散的悬浮液表现出正 ER 性能。由于介电性能的提高，随着热处理温度的升高，ER 性能得到增强。然而，尽管热干燥 PAN 颗粒具有比基体更高的电导率和介电常数，但它们的 ER 悬浮液表现出负 ER 行为，这与传导模型相反。XRD 结果表明，即使 ER 材料具有相同的分子结构，由于其结晶度，它们也可能表现出相反的 ER 行为。这一发现有望促进基于碳质 ER 材料的正 ER 和负 ER 悬浮液的发展。
